
<template>
    <div class="s-canvas">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>
<script>
    export default {
        name: 'SIdentify',
        props: {
            identifyCode: {
                type: String,
                default: '1234'
            },
            fontSizeMin: {
                type: Number,
                default: 20
            },
            fontSizeMax: {
                type: Number,
                default: 40
            },
            backgroundColorMin: {
                type: Number,
                default: 170
            },
            backgroundColorMax: {
                type: Number,
                default: 230
            },
            colorMin: {
                type: Number,
                default: 50
            },
            colorMax: {
                type: Number,
                default: 160
            },
            lineColorMin: {
                type: Number,
                default: 60
            },
            lineColorMax: {
                type: Number,
                default: 180
            },
            dotColorMin: {
                type: Number,
                default: 0
            },
            dotColorMax: {
                type: Number,
                default: 255
            },
            contentWidth: {
                type: Number,
                default: 118
            },
            contentHeight: {
                type: Number,
                default: 40
            }
        },
        methods: {
            // 生成一个随机数
            randomNum(min, max) {
                return Math.floor(Math.random() * (max - min) + min)
            },
            // 生成一个随机的颜色
            randomColor(min, max) {
                var r = this.randomNum(min, max);
                var g = this.randomNum(min, max);
                var b = this.randomNum(min, max);
                return 'rgb(' + r + ',' + g + ',' + b + ')'
            },
            drawPic() {
                var canvas = document.getElementById('s-canvas')
                var ctx = canvas.getContext('2d');
                ctx.textBaseline = 'bottom';
                // 绘制背景
                ctx.fillStyle = this.randomColor(
                    this.backgroundColorMin,
                    this.backgroundColorMax
                );
                ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
                // 绘制文字
                for (let i = 0; i < this.identifyCode.length; i++) {
                    this.drawText(ctx, this.identifyCode[i], i)
                }
                this.drawLine(ctx);
                this.drawDot(ctx)
            },
            drawText(ctx, txt, i) {
                ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
                ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei';
                var x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
                var y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
                var deg = this.randomNum(-40, 40);
                // 修改坐标原点和旋转角度
                ctx.translate(x, y);
                ctx.rotate(deg * Math.PI / 180);
                ctx.fillText(txt, 0, 0);
                // 恢复坐标原点和旋转角度
                ctx.rotate(-deg * Math.PI / 180);
                ctx.translate(-x, -y)
            },
            drawLine(ctx) {
                // 绘制干扰线
                for (let i = 0; i < 8; i++) {
                    ctx.strokeStyle = this.randomColor(
                        this.lineColorMin,
                        this.lineColorMax
                    )
                    ctx.beginPath();
                    ctx.moveTo(
                        this.randomNum(0, this.contentWidth),
                        this.randomNum(0, this.contentHeight)
                    )
                    ctx.lineTo(
                        this.randomNum(0, this.contentWidth),
                        this.randomNum(0, this.contentHeight)
                    )
                    ctx.stroke()
                }
            },
            drawDot(ctx) {
                // 绘制干扰点
                for (let i = 0; i < 100; i++) {
                    ctx.fillStyle = this.randomColor(0, 255)
                    ctx.beginPath()
                    ctx.arc(
                        this.randomNum(0, this.contentWidth),
                        this.randomNum(0, this.contentHeight),
                        1,
                        0,
                        2 * Math.PI
                    )
                    ctx.fill()
                }
            },
        },
        watch: {
            identifyCode() {
                this.drawPic()
            }
        },
        mounted() {
            this.drawPic()
        }
    }
</script>
<style scoped>
    #s-canvas{
        border-radius: 4px;
    }
</style>
